Examples of other prior couplings are described in U.S. Pat. No. 2,219,161 issued to M. Jacobs on Oct. 22, 1940, U.S. Pat. No. 2,999,700 issued to F. L. Smith on Sept. 12, 1961, U.S. Pat. No. 3,499,667 issued to A. Pfeuffer on March 10, 1970, U.S. Pat. No. 1,839,761 issued to A. R. Hutton on Jan. 5, 1932, U.S. Pat. No. 3,540,758 issued to J. Torres on Nov. 17, 1970, U.S. Pat. No. 3,610,654 issued to J. Torres on Oct. 5, 1971, U.S. Pat. No. 2,913,262 issued to H. A. De Cenzo et al on Nov. 17, 1959, and U.S. Pat. No. 3,228,714 issued to L. S. Dricksen on Jan. 11, 1966.
The type of coupling described in No. Pat. No. 3,776,579 is not satisfactory for interconnecting lines which convey jet fuel or other readily ionizable fluids because the coupling's deformable seal rings may electrically insulate the coupled sections of the line from each other. When this condition occurs, ionization of the jet fuel in the line may cause an electrostatic charge to build up on one of the coupled sections of the line. The stored charge gives rise to the hazard of electrical spark in the presence of vaporized fuel should it be discharged by grounding or by flexing the coupling in such a manner as to bring metallic parts of the coupling into contact with each other.
Various types of electrical jumpers (which are customarily referred to as bonding jumpers) have been proposed in the past to avoid this hazard. The bonding jumpers provide an electrically conductive metallic connection between the coupled sections of the line to prevent a potential or charge from building up on one of the coupled sections of the line relative to the other.
Prior to this invention exteriorly and interiorly mounted jumpers have been proposed for electrically interconnecting coupled sections of a fluid-conveying line.
External electrical jumpers customarily comprise a strip of usually flexible metal or a section of cable which is detachably secured by fasteners to the coupled ends of the fluid-conveying line or to flanges which are fixed to the adjacent ends of the coupled sections of the line. One example of an exteriorly mounted electrical jumper is described in U.S. Pat. No. 3,152,220 which issued to A. F. Gallacher on Oct. 6, 1964.
Exteriorly mounted electrical jumpers of the type described above are not satisfactory because they require assembly and disassembly each time it is desired to couple and uncouple the sections of the fluid-conveying line.
It has also been proposed to utilize a generally U-shaped spring clip jumper which is exteriorly clipped on a coupling and which has gripping legs yieldably engaging the coupling. This type of jumper also requires removal to uncouple the line. Additionally, the gripping legs of the spring clip are frequently bent permanently out of shape when they are grasped to spread them apart for removing the clip from the coupling and also for mounting the clip on the coupling.
Prior bonding jumpers which are mounted interiorly within the coupling may take the form of a leaf spring which is arranged to seat against and establish electrical continuity between the flanges on adjacent ends of the coupled sections of the fluid-conveying line. Also, metallic washers are sometimes interposed between adjacent flanged ends of fluid-conveying lines to establish an electrical circuit between the coupled ends of the line as shown, for example, in U.S. Pat. No. 2,407,076 which issued on Sept. 3, 1946 to J. R. Harkness and U.S. Pat. No. 2,783,297 which issued to L. M. Ewing on Feb. 26, 1957.
Bonding jumpers which are mounted interiorly of the coupling are disadvantageous because they cannot be seen from the exterior of the coupling. It therefore is not possible to determine whether the bonding jumper is mounted in place without disassembling the coupling itself.
The type of threadless coupling described in the U.S. Pat. No. 3,776,579 comprises a longitudinally split coupler which is releasably retained by a flexible clamping band in a coupling position around confronting flanges on the adjacent ends of the coupled sections of the fluid-conveying line. The clamping band, which is looped around the split coupler, has interengageable ends to circumferentially confine the coupler halves in their coupling positions on the flanges.
Toggle clamps or locks are generally easier to manipulate than the type of retaining or clamping band latch described in U.S. Pat. No. 3,776,579. However, various toggle clamps, which heretofore have been proposed for securing the ends of a clamping or retaining band in a coupling, can be latched improperly to result in leakage or release of the coupling. Additionally, known prior toggle latching arrangements which are suitable for clamping a retaining band in a coupling provide no safety lock to maintain the toggle clamp in its locking position.
Examples of prior toggle locks are described in the previously mentioned U.S. Pat. Nos. 3,228,714 and 2,913,262 and also in U.S. Pat. No. 3,333,302 which issued to R. Klima on Aug. 1, 1967.
In the coupling described in U.S. Pat. No. 3,776,579 the clamping band is fixed to the separately formed halves of the split coupler and bridges adjacent ends of the coupling halves to provide a yieldable hinge which allows the split coupler to be opened and closed for assembly and disassembly on the coupling flanges. This construction is disadvantageous because workers, in assembling or disassembling the coupling, sometimes spread the coupler halves so far apart that they permanently deform the clamping band in the yieldable hinge region which bridges the adjacent ends of the coupler halves.